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[babeltrace.git] / include / babeltrace / align.h
1 #ifndef _BABELTRACE_ALIGN_H
2 #define _BABELTRACE_ALIGN_H
3
4 /*
5 * BabelTrace align.h - alignment header
6 *
7 * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 *
9 * Permission is hereby granted, free of charge, to any person obtaining a copy
10 * of this software and associated documentation files (the "Software"), to deal
11 * in the Software without restriction, including without limitation the rights
12 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 * copies of the Software, and to permit persons to whom the Software is
14 * furnished to do so, subject to the following conditions:
15 *
16 * The above copyright notice and this permission notice shall be included in
17 * all copies or substantial portions of the Software.
18 *
19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
25 * SOFTWARE.
26 */
27
28 #include <babeltrace/compiler.h>
29 #include <unistd.h>
30 #include <limits.h>
31
32 #ifndef PAGE_SIZE /* Cygwin limits.h defines its own PAGE_SIZE */
33 #define PAGE_SIZE sysconf(_SC_PAGE_SIZE)
34 #endif
35
36 #define ALIGN(x, a) __ALIGN_MASK(x, (typeof(x))(a) - 1)
37 #define __ALIGN_MASK(x, mask) (((x) + (mask)) & ~(mask))
38 #define PTR_ALIGN(p, a) ((typeof(p)) ALIGN((unsigned long) (p), a))
39 #define ALIGN_FLOOR(x, a) __ALIGN_FLOOR_MASK(x, (typeof(x)) (a) - 1)
40 #define __ALIGN_FLOOR_MASK(x, mask) ((x) & ~(mask))
41 #define PTR_ALIGN_FLOOR(p, a) \
42 ((typeof(p)) ALIGN_FLOOR((unsigned long) (p), a))
43 #define IS_ALIGNED(x, a) (((x) & ((typeof(x)) (a) - 1)) == 0)
44
45 /*
46 * Align pointer on natural object alignment.
47 */
48 #define object_align(obj) PTR_ALIGN(obj, __alignof__(*(obj)))
49 #define object_align_floor(obj) PTR_ALIGN_FLOOR(obj, __alignof__(*(obj)))
50
51 /**
52 * offset_align - Calculate the offset needed to align an object on its natural
53 * alignment towards higher addresses.
54 * @align_drift: object offset from an "alignment"-aligned address.
55 * @alignment: natural object alignment. Must be non-zero, power of 2.
56 *
57 * Returns the offset that must be added to align towards higher
58 * addresses.
59 */
60 #define offset_align(align_drift, alignment) \
61 ({ \
62 MAYBE_BUILD_BUG_ON((alignment) == 0 \
63 || ((alignment) & ((alignment) - 1))); \
64 (((alignment) - (align_drift)) & ((alignment) - 1)); \
65 })
66
67 /**
68 * offset_align_floor - Calculate the offset needed to align an object
69 * on its natural alignment towards lower addresses.
70 * @align_drift: object offset from an "alignment"-aligned address.
71 * @alignment: natural object alignment. Must be non-zero, power of 2.
72 *
73 * Returns the offset that must be substracted to align towards lower addresses.
74 */
75 #define offset_align_floor(align_drift, alignment) \
76 ({ \
77 MAYBE_BUILD_BUG_ON((alignment) == 0 \
78 || ((alignment) & ((alignment) - 1))); \
79 (((align_drift) - (alignment)) & ((alignment) - 1); \
80 })
81
82 #endif /* _BABELTRACE_ALIGN_H */
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